1. Field of the Invention
The invention relates to a method for paying for services and/or goods and to an apparatus for carrying out the method.
Such methods are advantageously used for cash-less payment for those types of services and/or goods--for example when telephoning or filling up with fuel--the price of which is not fixed beforehand.
2. Description of the Prior Art
A prior method for payment for services and/goods is known comprising steps of, prior to a purchase of a service and/or goods, reading a usable amount from a credit balance means (credit balance carrier) and writing said useable amount into a memory; and, during said purchase, determining a running cost amount for said service and/or goods and storing back into said credit balance means an unused amount, wherein said unused amount is said difference between said usable amount and said cost amount. A method of this type is described in the preamble of claim 1 is known (EP 0 185 365 B1) in which an amount is written into a memory in a pre-paid credit balance card and reduced in the memory during performance of a service. When the performance of the service is completed, the reduced amount is written back into the credit balance card, whereby the performance of the service is paid for.
Without special measures it is not guaranteed that a service/goods purchased are actually paid for by a reduction in the credit balance on the credit balance card and that no credit balance greater than the credit balance less the value of the service/goods is written back into the memory of the credit balance card.